One of the world's highest navigable aqueducts has taken another step towards being awarded 'world wonder' status.

Consultants have been appointed to assess the historical significance of Pontcysyllte, near Wrexham.

Backers hope the landmark will join the list of Unesco World Heritage sites.

The list includes the Taj Mahal, the Great Wall of China and the Blaenavon industrial landscape in South Wales.

The aqueduct, built by engineer Thomas Telford, opened in 1805 and celebrations are planned in November for the bicentenary.

The 1,000 ft long structure which carries the Llangollen Canal above the Dee Valley is one of the region's biggest tourist attractions bringing in around 250,000 visitors a year by boat or on foot.

Two teams of consultants, examining both the aqueduct's historical significance and transport systems, have been asked to report back by the end of September.

Gaining World Heritage Status would be of great value to the local community as well as a real coup for the tourism profile of the county borough

Dr Dawn Roberts, Wrexham Council

Their findings will be critical in determining whether the aqueduct's bid to be included on the Unesco list - probably for 2007/8 - can move ahead.

Pontcysyllte was first identified by Unesco as a potential candidate in 1999.

Wrexham Council is jointly co-ordinating the bid with British Waterways, the structure's owners, the Welsh historic monuments body Cadw and the Royal Commission for Ancient Historic Monuments(Wales).

Dr Dawn Roberts, Wrexham council's economic development manager, said: "The aqueduct represents a great historical resource for Wrexham and gaining world heritage status would be of great value to the local community as well as a real coup for the tourism profile of the county borough."

Dr David Gwyn, one of the consultants carrying out the evaluation, said: "Pontcysyllte is already protected as an ancient monument and we are excited by the prospect of investigating its wider historical significance.

"The span construction of the aqueduct used an innovative technique for the time and, as a Welshman, I am doubly delighted to be involved in this project."

Revamp

Telford's aqueduct, which took 10 years to build at a cost of £45,000, was officially opened on 26 November 1805.

This November a year of celebrations will culminate in what the council is calling "a spectacular bicentenary event" at the site.

Last year the landmark underwent a £2m revamp.

Blaenavon and its industrial ironworks was the last Welsh site to gain World Heritage Status in 2000. Kew Gardens in London won the accolade in 2003.